Gazpromneft-Sakhalin specialists have presented a new technique in environmental control — active acoustic monitoring — to an audience of Russian and international acoustics specialists and marine biologists. The presentation took place during a working group of the International Union for the Conservation of Nature, with company scientists introducing academics to the results of environmental monitoring of grey whales in the Sea of Okhotsk.
Active acoustic monitoring was first used by Gazprom Neft during seismic surveys at its Ayashsky license block in 2019, with reflected acoustic signals being used to detect large marine mammals (cetaceans). Gazprom Neft’s advanced instrumental control methodologies proved of interest to scientists in terms of the benefits for marine animals’ safety underwater: active acoustics having never before been used to detect marine mammals during 3D-seismic surveys, in any country.
Active acoustics has advantages over traditional research methodologies and can be used under limited visibility, as well as in situations in which animals make no sound, or do so rarely. To eliminate the impacts of manmade noise on whales during geological prospecting, Gazprom Neft specialists examined the surrounding water using fishing sonar equipment installed on the side of the boat, prior to activating any seismic source. This led to four sightings of large marine mammals being recorded, with any sound sources being deactivated in time, thus avoiding eliminating any noise impacts on the whales.
The company uses standard environmental controls in addition to active acoustic monitoring, including visual observation and using thermal imaging cameras at night. Specialists were able to pinpoint 12 whales in 2019, using these tools.
Oil and gas companies operating in Sakhalin, together with experts from leading Russian scientific and research institutes, are involved in a joint programme monitoring grey whales and their habitations offshore in the Sea of Okhotsk. The programme includes four key research areas: photo-identification of grey whales; investigations into their distribution in feeding areas; investigations into the benthos (seabed flora and fauna) on which they subsist; and acoustic monitoring of unatural and man-made underwater noise. The programme has helped secure information that is now helping the conservation of grey whales and their habitats, as well as helping companies minimise potential production-related impacts on them. The number of grey whales offshore from the north—east of Sakhalin Island has been increasing every year following discoveries in the early 1980s, when their population numbered around 20. An expedition organised by Gazprom Neft in 2019 resulted in academics registering more than 550 individual whales.
The Ayashsky license block in the Sea of Okhotsk is located 55 kilometres offshore from Sakhalin Island, in the north—east of the island’s continental shelf, where sea depths can reach up to 90 metres. The Neptune field (with 415 million tonnes (mt) of reserves initially in place (RIIP)) was discovered at this license block in 2017, and the Triton field (with 137 mt RIIP) in 2018.